This invention relates to a three-dimensional image generator for generating images of natural objects such as waves on the surface of the sea or a forest blown by the wind, more particularly to a three-dimensional image generator capable of generating dynamic images in real time.
The modeling of natural scenery such as waves, clouds, mountains, and forests is an important field of computer graphics, having applications in such areas as animated movies, commercial advertising, and flight training simulation. The detail in such models is generated using stochastic (probabilistic) techniques, often founded on mathematical fractal (fractional dimension) theory.
One prior-art technique employs pairs of fractal or extended fractal waves representative of stochastic processes propagating in different directions. The waves in each pair are multiplied together and the products added to generate realistic images of three-dimensional natural scenes.
The generation of fractal images is a computationally intensive, time-consuming process, however. A minute and a half is required to produce a single, static image by the method above. Fractal techniques are therefore unsuitable for creating dynamic images (moving pictures), and are incapable of generating dynamic images in real time.
Many schemes for real-time output of three-dimensional moving images have been proposed, but they can only represent simple motions such as rotation, translation, reduction, and enlargement. They cannot duplicate complex, irregular motions such as ocean waves or a forest blowing in the wind.
Another problem in the prior art is that when a scene includes several types of natural objects, such as mountains, clouds, and sea, they must be generated separately, then combined. This further complicates the creation of real-time dynamic images.